Main menu

Tag Archives: Acoustics

Post navigation

A (sometimes) weekly post of riveting reads from my travels around the internet this week! A selection of links, blogs, news articles, scholarly articles and images I am currently loving.

Researches delve into the nuances of sperm whale vocalisations: The scientists findings show cultural transmission of the vocalisations through generations are key and suggest evidence of human-like complex culture and multi-level social structures in sperm whale clans.

Shark alarm in Perth: Curtin University (where I am visiting) and Mullaloo Surf Life Saving Club have joined together to create BeachLAB. The alert system works by recognising marine animals there were previously tagged with acoustic tags and are travelling though the area. See a video about it here.

What have you been reading this week? Let me know in the comments below.

You can also follow along on the Deep Blue Conversations Facebook Page. I post interesting articles related to marine conservation, share awesome stories as well as photos from the marine conservation and environmental world in general. Come on over and have a look! I also have Twitter come and join the conversation you can find me as @Leila_Lula!

Just like the first day of school and the first piece of art you bring home, your first paper as a scientist is a pretty big deal and I am super excited about mine. This paper will always be very special to me as it is the first piece of work that I a fully sending out into the world with my colleagues to be continually and forever more judged by my peers.

Ta-Dah!

This paper is also from a project exceedingly close to my heart it is a topic that I have been interested in for a long time and the road to its completion was not always smooth but what is life without a challenge and out of it has come a piece of work that myself and my colleagues are exceptionally proud of.

It is the result of two years of data collection to look at the different vocalisations produced by the killer whale population in the Bremer Canyon, Western Australia. My involvement was full time in the second year, where I was involved in data collection, data analysis and manuscript preparation.

What did we see I hear you wondering out loud…? Well we used K-Means clustering analysis to group the calls into categories with the most similar acoustic features. We looked at whistles (frequency modulated, tonal sounds, with or without harmonic overtones) and burst pulses (consist of rapidly repeated pulses with inter-pulse intervals shorter than in echolocation click trains). We did also detect clicks while collecting data however they were not a focus of this paper. Through the analysis the calls have been separated into nine different Bremer Canyon call groups four for whistles, three for burst pulses, one for whistles that are pulsed in the middle, and the final group consists of burst pulse to whistle transitions and vice versa.

This paper is unique in that it is the first paper to describe the vocalisation of killer whales in Australia. The vocalisations are the topic of my colleague Bec Wellard’s PhD and there will, I am sure, be many more exciting developments to come in the realm of Australian killer whale acoustics. My focus is now shifting more in the direction of ecology, population studies and conservation so keep your eyes peeled to see what comes with that.

How did you feel after your first paper was published? Did you keep a close eye on citation indexes and metrics? Was it a thrill or a relief once the paper was submitted and accepted?

I know I am definitely looking forward to working fully on my next paper now!

You can also follow along on the Deep Blue Conversations Facebook Page. I post interesting articles related to marine conservation, share awesome stories as well as photos from the marine conservation and environmental world in general. Come on over and have a look! I also have Twitter come and join the conversation you can find me as @Leila_Lula

Wow, Wow, Wow! It has been a busy few weeks since I arrive in Perth. First it was non-stop preparing equipment and organising ourselves and then it was diving head first into Bremer Bay life and data collection. We arrived in Bremer Bay in Western Australia on the 8th February and were out on the water 7.30 am on the 9th.

We are here to collect data on this unique aggregation of killer whales (Orcinus orca) that occurs every year between January and March a 2 hour steam offshore from Bremer Bay where the water depth drops quickly from around 80 metres to over 800 metres and deeper. Here there are numerous underwater canyons where the depth can reach 3000 metres or more.

Now back to the cetaceans…So very little is known about the Australian killer whale population and we hope to be able to change this by building up a picture of where they are, and what they are doing, while also deciphering the individuals we are seeing through fin identification and using hydrophones to determine their acoustic repertoire. It is an amazing project.

On the 10th February we deployed two noise loggers which, are long term underwater recording devices that record on a schedule and allow us to build a picture of what is happening when we are not there through the acoustics of the region. From these we will be able to build a picture of natural ocean noise such as waves, wind and, marine mammals as well as anthropogenic noise from boats and far off seismic activity.

Alongside, the data collection on marine mammals we also plan to use a mounted sonar to record the biomass in the region especially when marine mammals are feeding and a CDT (Conductivity, Depth and Temperature) instrument to record salinity, depth, temperature as well as fluorescence to gain a better understanding of what makes the ecosystem work. Further, to all this amazing equipment we have also had sonobuoys donated to us by L3 which, will allow us to passively and in real-time monitor the acoustic environment while we are at sea. This will in theory enable us to hear what is happening underwater while we see what is happening above water and potentially determine what we are missing as well as what is happening (acoustically) up to 5 km away.

We are only just getting started on this project but, from it I hope to be able to build up a PhD thesis that I can really get excited about. Alongside killer whales there have been sightings of beaked whales, sperm whales and pilot whales in pervious seasons. Just yesterday we spotted a pod of between 20 and 30 long-finned pilot whales (Globicephala melas) where it looked like the sea was bubbling with activity. I cannot wait to see what tomorrow brings.

A bubbling sea of long finned pilot whales.

We had a windy day off today where we tried to catch up on some data, visited the beautiful remote beaches of Western Australia and do all our laundry which, was nice especially as we don’t know when we might get another day for data catch up!

I will try and upload some video footage and updates from the field as our crazy hectic time here in Bremer Bay flies back.

You can also follow along on the Deep Blue Conversations Facebook Page. I post interesting articles related to marine conservation, share awesome stories as well as photos from the marine conservation and environmental world in general. Come on over and have a look!

Southern Resident Killer Whales (SRKW) have been in the news a lot lately (well the scientific and environmental news). A pregnant female washed up dead on a beach in British Colombia at the beginning of December and even more tragically was pregnant at the time which, has brought them further into the public eye.

All the SRKW belong to one clan – or “extended family” – therefore they are all related. This clan – J Clan – is made up of three pods – J, K , and L – with 77 individuals of which, only 12 are reproductive females. Four individuals of the population were lost this year which is a big blow for this small clan.

The populations is struggling to recover their numbers back to a viable level and in this post I will discuss why.

Prey Availability

Chinook Salmon. Photo: NOAA.

SRKW favour Chinook Salmon almost exclusively feeding on it. The problem is that Chinook salmon are struggling to spawn and their numbers are also dwindling due to unsuitable habitats to spawn in. This means that SRKW are facing a depleted prey source and nutritional stress.

Nutritional stress has been shown to affect Glucocorticoids (cortisol) and thyroid hormone in killer whales. Glucocorticoids affect glucose metabolism for a quick response to an immediate threat over a short time frame (indicator of a short term stress), while thyroid hormone lowers metabolism to conserve energy stores over a longer time frame (indicator of long term/sustained stress).

Chinook salmon decline has been caused by activities such as logging and road construction have reduced the habitat condition degrading, fragmenting and eliminating key areas. To turn around their decline river habitats need to be restored to encourage spawning of salmon. This includes the removal/modification of dams on streams and the improvement of water quality and flow.

This issue can be fixed and would be a positive for both the killer whales and local fishermen.

In the middle of the last century the SRKW populations took a large hit when many members and sometimes whole families were removed in the live-capture industry.
Individuals/groups were removed to be put on display. With the removal of whole family groups the structure and populations numbers were severely disrupted. The SRKW were the most affected populations with 36 whales collected and at least 11 dying. There is nothing we can do now to correct this however there is a ban on the removal of all individuals in North America.